Male middle- and long-distance runners (N = 18) performed two supra-VO2max treadmill tests, one in normoxia and one after four hours of exposure to normobaric hypoxia (15% O2). Maximal accumulated oxygen (MAOD) deficit was measured.

Hypoxia produced a non-significant increase in MAOD of 9%. Maximal capillary lactate and ammonia concentration decreased significantly. Reduction in time-to-exhaustion was significantly related to decrement in oxygen uptake during exercise in hypoxia.

Implication. Performance during exhaustive supra-VO2max exercise in moderate hypoxia is not impaired by changes in anaerobic capacity. Very short sprint performances should not be affected by moderate hypoxia.